KR20100085732A - Organic light emitting diode display - Google Patents

Abstract

PURPOSE: An organic light emitting diode display is provided to minimize the loss of a light which is emitted from an organic light-emitting layer. CONSTITUTION: A first common electrode(730) is formed on an organic light emitting layer. A transmitting film(600) is formed on the first common electrode. A second common electrode(750) is formed on a transparent film. A selective reflective film(585) is formed on the second common electrode. A polarizing plate(581) is formed on a reflective film. A phase delay plate(583) is arranged between the polarizer and the second common electrode.

Description

Organic Light Emitting Display {ORGANIC LIGHT EMITTING DIODE DISPLAY}

The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device having improved visibility by effectively suppressing external light reflection.

The organic light emitting diode display includes a plurality of organic light emitting diodes having a hole injection electrode, an organic emission layer, and an electron injection electrode. In the organic light emitting layer, light is emitted by energy generated when an exciton generated by combining electrons and holes falls from an excited state to a ground state, and the organic light emitting diode display forms an image by using the energy.

Therefore, the organic light emitting diode display has a self-luminous property and, unlike the liquid crystal display, does not require a separate light source, thereby reducing thickness and weight. In addition, the organic light emitting diode display has attracted attention as a next-generation display device for portable electronic devices because it exhibits high quality characteristics such as low power consumption, high luminance, and high response speed.

In general, various electrodes and metal wires of the organic light emitting diode display reflect light introduced from the outside. Due to the external light reflection, the organic light emitting diode display has a problem of poor display and contrast and deterioration of display characteristics.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the background art, and to provide an organic light emitting display device which suppresses external light reflection and improves visibility while minimizing the loss of light emitted from the organic light emitting layer to the outside.

An organic light emitting diode display according to an exemplary embodiment of the present invention includes a substrate member, a pixel electrode formed on the substrate member, an organic emission layer formed on the pixel electrode, a first common electrode formed on the organic emission layer, and an upper portion of the first common electrode. A transmissive film formed on the transparent film, a second common electrode formed on the transmissive film, a selective reflective film formed on the second common electrode, a polarizing plate formed on the selective reflective film, and a phase delay disposed between the polarizing plate and the second common electrode. Includes the edition.

The selective reflection film may be a cholesteric liquid crystal (CLC) film, and the phase retardation plate may be disposed between the polarizer and the cholesteric liquid crystal film.

The cholesteric liquid crystal film may pass one of left circularly polarized light and right circularly polarized light, and reflect the other.

The light linearly polarized through the polarizing plate may change into circular polarized light when passing through the phase retardation plate.

The phase retardation plate may be a quarter wave plate, and the pier between the optical axis of the phase retardation plate and the polarization axis of the polarizing plate may be 45 degrees.

The selective reflective film may be a reflective polarizing film, and the phase retardation plate may be disposed between the organic light emitting device and the reflective polarizing film.

The polarizing plate and the reflective polarizing film may have the same polarization axis.

Light linearly polarized through the reflective polarizing film may change into circularly polarized light when passing through the phase retardation plate.

The phase retardation plate may be a quarter wave plate, and the pier between the optical axis of the phase retardation plate and the polarization axis of the polarizing plate may be 45 degrees.

At least one of the first common electrode and the second common electrode may be formed as a semi-transmissive layer.

The semi-permeable membrane may be made of at least one metal of magnesium (Mg), silver (Ag), calcium (Ca), lithium (Li), chromium (Cr), and aluminum (Al).

The organic light emitting diode display may further include a pixel defining layer formed on the substrate member with an opening that exposes the pixel electrode, and the pixel defining layer may have a black or gray color.

The pixel defining layer may be disposed under the first common electrode.

According to the present invention, the organic light emitting diode display can suppress reflection of external light, thereby improving visibility and minimizing the loss of light emitted from the organic light emitting layer to the outside.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to the illustrated.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

In addition, in the various embodiments, components having the same configuration are represented by the same reference symbols in the first embodiment. In the other embodiments, only components different from those in the first embodiment will be described .

In addition, in the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. Whenever a portion such as a layer, film, region, plate, or the like is referred to as being "on" or "on" another portion, it includes not only the case where it is "directly on" another portion but also the case where there is another portion in between. On the contrary, when a part is "just above" another part, there is no other part in the middle.

In addition, in the accompanying drawings, an active matrix (AM) type organic light emitting display having a 2Tr-1Cap structure having two thin film transistors (TFTs) and one capacitor in one pixel. Although illustrated, the present invention is not limited thereto. Accordingly, the organic light emitting diode display may include three or more thin film transistors and two or more capacitors in one pixel, and may be formed to have various structures by further forming additional wires. Here, a pixel refers to a minimum unit for displaying an image, and the organic light emitting diode display displays an image through a plurality of pixels.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

1 and 2, the organic light emitting diode display 100 according to the first exemplary embodiment of the present invention includes a switching thin film transistor 10, a driving thin film transistor 20, and a storage device 80 in one pixel. And an organic light emitting diode (OLED) 70. The OLED display 100 further includes a gate line 151 disposed along one direction, a data line 171 and a common power line 172 that are insulated from and cross the gate line 151. In general, one pixel may be defined as a boundary between the gate line 151, the data line 171, and the common power line 172. However, the pixel is not limited to the above definition.

The organic light emitting diode 70 includes a pixel electrode 710, an organic emission layer 720 formed on the pixel electrode 710, and a common electrode 730 formed on the organic emission layer 720. Here, the pixel electrode 710 is a positive electrode which is a hole injection electrode, and the common electrode 730 is a negative electrode which is an electron injection electrode. However, the first embodiment according to the present invention is not necessarily limited thereto, and the pixel electrode 710 may be a cathode and the common electrode 730 may be an anode according to a driving method of the organic light emitting diode display 100. Holes and electrons are injected into the organic emission layer 720 from the pixel electrode 710 and the common electrode 730, respectively. When the exciton, in which the injected holes and electrons combine, falls from the excited state to the ground state, light emission occurs.

The power storage device 80 includes a first power storage plate 158 and a second power storage plate 178 disposed with the gate insulating layer 140 interposed therebetween.

The switching thin film transistor 10 includes a switching semiconductor layer 131, a switching gate electrode 152, a switching source electrode 173, and a switching drain electrode 174, and the driving thin film transistor 20 includes the driving semiconductor layer 132. ), A driving gate electrode 155, a driving source electrode 176, and a driving drain electrode 177.

The switching thin film transistor 10 is used as a switching element for selecting a pixel to emit light. The switching gate electrode 152 is connected to the gate line 151. The switching source electrode 173 is connected to the data line 171. The switching drain electrode 174 is spaced apart from the switching source electrode 173 and is connected to the first capacitor plate 158.

The driving thin film transistor 20 applies driving power to the pixel electrode 710 for emitting the organic light emitting layer 720 of the organic light emitting element 70 in the selected pixel. The driving gate electrode 155 is connected to the first capacitor plate 158. The driving source electrode 176 and the second power storage plate 178 are connected to the common power line 172, respectively. The driving drain electrode 177 is connected to the pixel electrode 710 of the organic light emitting diode 70 through the contact hole 182.

By such a structure, the switching thin film transistor 10 operates by a gate voltage applied to the gate line 151 to transfer a data voltage applied to the data line 171 to the driving thin film transistor 20. . The voltage corresponding to the difference between the common voltage applied to the driving thin film transistor 20 from the common power supply line 172 and the data voltage transmitted from the switching thin film transistor 10 is stored in the power storage element 80, and the power storage element 80 The current corresponding to the voltage stored in the) flows through the driving thin film transistor 20 to the organic light emitting device 70 to emit light.

In addition, the organic light emitting diode display 100 further includes a pixel defining layer 190, a sealing member 210, and an optical member 58.

The pixel defining layer 190 has an opening that exposes the pixel electrode 710, and the pixel electrode 710 is formed at a position corresponding to the opening of the pixel defining layer 190. In addition, the pixel defining layer 190 may have a black or gray color. Accordingly, the pixel defining layer 190 suppresses the reflection of the light incident from the outside. Meanwhile, in the first embodiment of the present invention, the pixel defining layer 190 has a black or gray color, but is not necessarily limited thereto. Therefore, the pixel defining layer 190 may not have a color.

The sealing member 210 is bonded between the substrate member 111 and sealed between the organic light emitting elements 70. The sealing member 210 covers and protects the thin film transistors 10 and 20, the organic light emitting element 70, and the like formed on the substrate member 111 to be sealed from the outside. Here, the configuration except for the sealing member 210 and the optical member 58 is referred to as the display substrate 110. As the sealing member 210, an insulating substrate made of glass, plastic, or the like may be used.

The optical member 58 suppresses reflection of external light to improve visibility of the organic light emitting diode display 100, and minimizes loss of light emitted from the organic light emitting diode 70 to the outside. The optical member 58 includes a selective reflection film 585 formed on the organic light emitting element 70, a phase delay plate 583 formed on the selective reflection film 585, and a polarizing plate 581 formed on the phase delay plate 583. ). Further, in the first embodiment of the present invention, the optical member 58 is formed on the sealing member 210, but is not limited thereto. Therefore, the optical member 58 may be formed between the sealing member 210 and the organic light emitting element 70.

The polarizing plate 581 has a polarization axis and linearly polarizes light in the polarization axis direction. Specifically, the polarizing plate 581 passes light that coincides with the polarization axis, and absorbs light that does not coincide with the polarization axis. Therefore, when light passes through the polarizing plate 581, it is linearly polarized in the polarization axis direction.

The phase retardation plate 583 is a quarter wave plate, and the phase retardation plate 583 has an optical axis that is shifted by about 45 degrees from the polarization axis of the polarizing plate 581. That is, the pier between the optical axis of the phase retardation plate 583 and the polarization axis of the polarizing plate 581 is about 45 degrees. Accordingly, light linearly polarized through the polarizing plate 581 becomes circularly polarized light while passing through the phase retardation plate 583. As the pier between the optical axis of the phase retardation plate 583 and the polarization axis of the polarizing plate 581 approaches 45 degrees, the linearly polarized light passing through the polarizing plate 581 becomes closer to the circularly polarized light while passing through the phase retardation plate 583.

As the selective reflection film 585, a cholesteric liquid crystal (CLC) film is used. Hereinafter, in the first embodiment of the present invention, the selective reflection film 585 is called a cholesteric liquid crystal film.

The cholesteric liquid crystal forms a layered structure like the smectic liquid crystal, but the molecules of the long axis have an equilibrium arrangement similar to that of the nematic liquid crystal in plane. Specifically, in one plane, thin and long molecules are arranged neatly in the direction of the major axis, and the structure in which the molecular axes are slightly deviated as the molecules progress in the direction perpendicular to the plane, that is, the molecules The arrangement is like a spiraling helical shape. Therefore, the whole liquid crystal has a spiral structure. Accordingly, the cholesteric liquid crystal has characteristics such as optical sensitivities, selective light scattering, and circular polarization dichroism.

Therefore, the cholesteric liquid crystal film 585 can selectively transmit or reflect circularly polarized light. In the first embodiment of the present invention, the cholesteric liquid crystal film 585 transmits right circularly polarized light and reflects left circularly polarized light.

In addition, the organic light emitting diode 70 of the organic light emitting diode display 100 further includes a transmission film 600 formed on the common electrode 730 and an additional common electrode 750 formed on the transmission film 600. do. Hereinafter, the common electrode 730 is called a first common electrode, and the additional common electrode 750 is called a second common electrode. Here, the first common electrode 730 is formed on the organic emission layer 720 and the pixel defining layer 190.

The first common electrode 730 and the second common electrode 750 are formed of a transflective film. However, the first embodiment according to the present invention is not limited thereto. Therefore, only one of the first common electrode 730 and the second common electrode 750 may be formed as a transflective layer, and the other may be formed transparently.

The transmission membrane 600 is in close contact with both of the first common electrode 730 and the second common electrode 750, respectively. That is, no interface with air exists between the transmission membrane 600, the first common electrode 730, and the second common electrode 750. Thus, a considerable amount of light introduced from the outside is extinguished by the destructive interference caused by reflection between the first common electrode 730 and the second common electrode 750. In this case, in order for the destructive interference of light to occur effectively between the first common electrode 730 and the second common electrode 750, the transmission membrane 600 should have an appropriate refractive index and thickness. The refractive index and thickness of the permeable membrane 600 will be described in detail with reference to Formula 1 to be described later.

As described above, the organic light emitting diode display 100 emits external light through the optical member 58 and the first common electrode 730, the transmission layer 600, the second common electrode 750, and the pixel defining layer 190. The visibility can be improved by suppressing reflection.

Hereinafter, the structure of the organic light emitting diode display 100 according to the first exemplary embodiment of the present invention will be described in detail with reference to FIG. 2. 2 illustrates the organic light emitting diode display 100 centering on the driving thin film transistor 20, the organic light emitting diode 70, and the power storage element 80.

Hereinafter, the structure of the thin film transistor with the driving thin film transistor 20 will be described in detail. In addition, the switching thin film transistor 10 briefly describes only differences from the driving thin film transistor.

The substrate member 111 is formed of an insulating substrate made of glass, quartz, ceramic, plastic, or the like. However, the present invention is not limited thereto. Therefore, the substrate member 111 may be formed of a metallic substrate made of stainless steel or the like.

The buffer layer 120 is formed on the substrate member 111. The buffer layer 120 serves to prevent infiltration of impurities and planarize the surface, and may be formed of various materials capable of performing such a role. For example, the buffer layer 120 may be any one of a silicon nitride (SiNx) film, a silicon oxide (SiO ₂ ) film, and a silicon oxynitride (SiOxNy) film. However, the buffer layer 120 is not necessarily required and may be omitted depending on the type of the substrate member 111 and the process conditions.

The driving semiconductor layer 132 is formed on the buffer layer 120. The driving semiconductor layer 132 is formed of a polycrystalline silicon film. In addition, the driving semiconductor layer 132 may include a channel region 135 that is not doped with impurities, and a source region 136 and a drain region 137 formed by p + doping to both sides of the channel region 135. At this time, the doped ionic material is a P-type impurity such as boron (B), and mainly B ₂ H ₆ is used. Here, such impurities vary depending on the type of thin film transistor.

In the first exemplary embodiment of the present invention, a thin film transistor having a PMOS structure using P-type impurities is used as the driving thin film transistor 20, but is not limited thereto. Therefore, both the NMOS structure or the CMOS structure thin film transistor may be used as the driving thin film transistor 20.

In addition, although the driving thin film transistor 20 shown in FIG. 2 is a polycrystalline thin film transistor including a polysilicon film, the switching thin film transistor 10 not shown in FIG. 2 may be a polycrystalline thin film transistor and an amorphous thin film transistor including an amorphous silicon film. It may be.

A gate insulating layer 140 formed of silicon nitride (SiNx) or silicon oxide (SiO ₂ ) is formed on the driving semiconductor layer 132. A gate wiring including the driving gate electrode 155 is formed on the gate insulating layer 140. The gate wiring further includes a gate line 151 (shown in FIG. 1), a first power storage plate 158 (shown in FIG. 1), and other wiring. In addition, the driving gate electrode 155 may be formed to overlap at least a portion of the driving semiconductor layer 132, particularly the channel region 135.

An interlayer insulating layer 160 covering the driving gate electrode 155 is formed on the gate insulating layer 140. The gate insulating layer 140 and the interlayer insulating layer 160 have through holes that expose the source region 136 and the drain region 137 of the driving semiconductor layer 132. The interlayer insulating film 160 is formed of silicon nitride (SiNx), silicon oxide (SiO ₂ ), or the like, like the gate insulating film 140.

The data line including the driving source electrode 176 and the driving drain electrode 177 is formed on the interlayer insulating layer 160. The data wiring further includes a data line 171, a common power supply line 172, a second power storage plate 178 (shown in FIG. 1), and other wiring. The driving source electrode 176 and the driving drain electrode 177 are connected to the source region 136 and the drain region 137 of the driving semiconductor layer 132 through through holes, respectively.

As such, the driving thin film transistor 20 including the driving semiconductor layer 132, the driving gate electrode 155, the driving source electrode 176, and the driving drain electrode 177 is formed.

The configuration of the driving thin film transistor 20 is not limited to the above-described example, and may be variously modified to a known configuration that can be easily implemented by those skilled in the art.

The planarization layer 180 covering the data lines 171, 172, 176, and 177 is formed on the interlayer insulating layer 160. The planarization layer 180 serves to eliminate the step difference and planarize in order to increase the luminous efficiency of the organic light emitting element 70 to be formed thereon. In addition, the planarization layer 180 has a contact hole 182 exposing a part of the drain electrode 177.

The planarization layer 180 may be an acrylic resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimide resin, or an unsaturated polyester resin. (unsaturated polyesters resin), poly (phenylenethers) resin, poly (phenylenesulfides) resin, and benzocyclobutene (benzocyclobutene (BCB)) may be made of one or more materials. .

The pixel electrode 710 of the organic light emitting diode 70 is formed on the planarization layer 180. The pixel electrode 710 is connected to the drain electrode 177 through the contact hole 182 of the planarization layer 180.

In addition, a pixel defining layer 190 having an opening exposing the pixel electrode 710 is formed on the planarization layer 180. That is, the pixel electrode 710 is disposed to correspond to the opening of the pixel defining layer 190.

The pixel defining layer 190 has a black or gray color. In addition, the pixel defining layer 190 may be made of a resin such as polyacrylates and polyimides, and a pigment contained in the resin.

An organic emission layer 720 is formed on the pixel electrode 710 in the opening of the pixel definition layer 190, and a first common electrode 730 is formed on the pixel definition layer 190 and the organic emission layer 720.

As such, the organic light emitting diode 70 including the pixel electrode 710, the organic emission layer 720, and the first common electrode 730 is formed. In addition, in the first embodiment according to the present invention, the organic light emitting diode 70 further includes a transmissive film 600 and a second common electrode 750.

The transmissive layer 600 is formed on the first common electrode 730. As the permeable membrane 600, an organic membrane or an inorganic membrane may be used. In the organic light emitting diode display 100 according to the first exemplary embodiment, the organic layer is used as the transmission layer 600. The permeable membrane 600 has an average thickness within an appropriate range. In this case, the thickness of the permeable membrane 600 is determined according to the refractive index of the permeable membrane 600.

The second common electrode 750 is formed on the transmission membrane 600. The first common electrode 730 and the second common electrode 750 are formed of a transflective film. Semi-transmissive layers used as the first common electrode 730 and the second common electrode 750 are magnesium (Mg), silver (Ag), calcium (Ca), lithium (Li), chromium (Cr), and aluminum (Al). ) Is formed of one or more metals.

In addition, the first common electrode 730 and the second common electrode 750 have an appropriate reflectance to effectively emit light generated in the organic light emitting device 70 and minimize reflection of light introduced from the outside. For example, the first common electrode 730 may have a reflectance of 50% or less, and the second common electrode 750 may have a reflectance of 30% or less.

The transmission membrane 600 is in close contact with both of the first common electrode 730 and the second common electrode 750. That is, no interface with air exists between the transmission membrane 600, the first common electrode 730, and the second common electrode 750.

In addition, the transmission membrane 600 has a suitable thickness and refractive index so that the destructive interference effectively occurs by the reflection of light between the first common electrode 730 and the second common electrode 750.

The thickness and refractive index of the transmission film 600 may be set through the following formula derived from the cancellation interference condition of the reflected light.

Formula 1

d = λ / 4ndcosθ

Where d is the distance between the two surfaces to be reflected. That is, the distance between the first common electrode 730 and the second common electrode 750 is the thickness of the permeable membrane 600. n is the refractive index of the transmission film 600, and θ is the incident angle of light. λ is the wavelength of the reflected light.

In this formula, the wavelength of visible light and the refractive index of the material used as the transmission membrane 600 are substituted. In addition, when the average angle of incidence of external light is about 30 degrees to about 45 degrees, an average thickness of the transmission membrane 600 may be calculated. That is, according to the kind of material used as the permeable membrane 600, the permeable membrane 600 is set to have an appropriate thickness. On the contrary, in order to form the permeable membrane 600 to a desired thickness, the permeable membrane 600 may be formed of a material having an appropriate refractive index.

According to this structure, the light from the outside through the second common electrode 750 toward the first common electrode 730 is partially reflected by the first common electrode 730 is directed to the second common electrode 750 again. . Some of the light directed to the second common electrode 750 passes through the second common electrode 750 and is emitted to the outside, and the other is reflected again to be directed to the first common electrode 730. As described above, light introduced from the outside is reflected between the first common electrode 730 and the second common electrode 750 with the transmissive layer 600 interposed therebetween, and a large amount of destructive interference occurs. Accordingly, the organic light emitting diode display 100 may improve visibility by suppressing reflection of external light.

In addition, as described above, the first common electrode 730 and the second common electrode 750 are formed in a transflective type. However, the organic light emitting diode display 100 according to the first exemplary embodiment is not limited thereto. Therefore, any one of the first common electrode 730 and the second common electrode 750 may be formed in a transmissive type. On the other hand, the pixel electrode 710 is formed of any one of a transmissive type, a transflective type, and a reflective type.

According to the types of materials forming the pixel electrode 710, the first common electrode 730, and the second common electrode 750, the organic light emitting diode display 100 may be top emission type, bottom emission type, or double emission type. This can be Meanwhile, the organic light emitting diode display 100 according to the first exemplary embodiment of the present invention is formed as a top emission type. That is, the organic light emitting diode 70 emits light toward the first common electrode 730 and the second common electrode 750 to display an image.

As the transparent conductive material, materials such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium oxide (In ₂ O ₃ ) may be used. Reflective materials include lithium (Li), calcium (Ca), lithium fluoride / calcium (LiF / Ca), lithium fluoride / aluminum (LiF / Al), aluminum (Al), silver (Ag), magnesium (Mg ), Or a material such as gold (Au) can be used.

The organic emission layer 720 is made of a low molecular organic material or a high molecular organic material. The organic light emitting layer 720 includes a hole-injection layer (HIL), a hole-transporting layer (HTL), a light-emitting layer, an electron-transportiong layer (ETL), and an electron-injection layer (electron-electron-layer). It is formed of a multilayer including an injection layer (EIL). That is, the hole injection layer is disposed on the pixel electrode 710 serving as an anode, and the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer are sequentially stacked thereon.

The sealing member 210 is disposed on the organic light emitting element 70. The sealing member 210 is disposed to face the substrate member 111 to cover the thin film transistor 20 and the organic light emitting element 70.

The optical member 58 is formed on the sealing member 210. The optical member 58 includes a cholesteric liquid crystal film 585, a phase retardation plate 583, and a polarizing plate 581 which are sequentially arranged on the sealing member 210. The optical member 58 suppresses reflection of external light, thereby improving visibility of the organic light emitting diode display 100 and minimizing loss of light emitted from the organic light emitting layer 720 to the outside.

Hereinafter, the light emitted from the organic light emitting layer 720 to the outside while the optical member 58 of the organic light emitting diode display 100 according to the first exemplary embodiment of the present invention effectively suppresses reflection of external light. Let's look at the principle of minimizing losses.

First, referring to FIG. 3, a path of light flowing into the inside through the optical member 58 from the outside will be described.

External light is linearly polarized in the direction of the polarization axis of the polarizing plate 581 while passing through the polarizing plate 581. The light which becomes linearly flat light passes through the phase retardation plate 583 which is a quarter wave plate, and changes into circularly polarized light. At this time, the optical axis of the phase retardation plate 583 is shifted by 45 degrees from the polarization axis of the polarizing plate 581. That is, the angle of intersection between the optical axis of the phase retardation plate 583 and the polarization axis of the second polarizing plate 581 is 45 degrees.

As described above, since the intersection between the axial direction of the linearly-lighted light and the optical axis direction of the phase retardation plate 583 forms 45 degrees, the linearly polarized light changes to circularly polarized light while passing through the phase retardation plate 583. In this case, circularly polarized light is right circularly polarized light. However, the first embodiment according to the present invention is not limited thereto. Therefore, the phase retardation plate 583 may be disposed so that the light passing through the phase retardation plate 583 becomes left circularly polarized light.

The right polarized light passes through the cholesteric liquid crystal film 585 as it is. The cholesteric liquid crystal film 585 transmits right circularly polarized light and reflects left circularly polarized light. However, the first embodiment according to the present invention is not limited thereto. Accordingly, the cholesteric liquid crystal film 585 may pass left circularly polarized light and reflect right circularly polarized light. In this case, however, the light passing through the phase delay plate 583 should be left circularly polarized light. That is, the cholesteric liquid crystal film 585 must pass circularly polarized light through the polarizing plate 581 and the phase retardation plate 583.

The right circularly polarized light that has passed through the cholesteric liquid crystal film 585 is reflected between the second common electrode 750 and the first common electrode 730 and is substantially extinguished by the destructive interference as described above. In addition, some light is reflected from the second common electrode 750, the first common electrode 730, the pixel electrode 710, and the like and is directed back to the cholesteric liquid crystal film 585. At this time, the light that is the right circularly polarized light is changed to the left circularly polarized light. Therefore, light does not pass through the cholesteric liquid crystal film 585 and is reflected back to the second common electrode 750. In addition, while reflected between the second common electrode 750 and the first common electrode 730, a considerable amount of disappearance due to destructive interference.

Again, the light that is left circularly polarized while being reflected from the second common electrode 750, the first common electrode 730, the pixel electrode 710, or the like is now converted into right circularly polarized light. The circularly polarized light passes through the cholesteric liquid crystal film 585 and passes through the phase retardation plate 583 to be changed into linearly polarized light. At this time, the linearly contiguous light has substantially the same axial direction as the polarization axis of the polarizing plate 581. Here, the expression "substantially the same" is because light shows slightly different behavior for each wavelength band. Light belonging to the wavelength band of the visible light is in substantially the same direction as the polarization axis of the polarizing plate 581. Therefore, the linearly polarized light passes through the polarizer 581 and is emitted to the outside.

As described above, since external light passes through the optical member 58 and is reflected between the second common electrode 750 and the first common electrode 730 several times, the light is extinguished by the destructive interference. 100 can effectively suppress external light reflection.

In addition, as illustrated in FIG. 2, the pixel defining layer 190 having a black or gray color may absorb light to more effectively suppress external light reflection.

Next, the path of light emitted from the organic emission layer 720 to the outside will be described with reference to FIG. 4.

The light emitted from the organic emission layer 720 passes through the first common electrode 730, the transmissive film 600, and the second common electrode 750 in order to be directed to the cholesteric liquid crystal film 585. At this time, light is a state in which various phases are mixed. The light of the right circularly polarized light component of the light passing through the second common electrode 750 passes through the cholesteric liquid crystal film 585 as it is and is directed to the phase retardation plate 583, and the light of the left circularly polarized light component is reflected and is again reflected. To the common electrode 750. Light passing through the cholesteric liquid crystal film 585 is linearly polarized while passing through the phase retardation plate 583, and the linearly polarized light is emitted to the outside through the polarizing plate 581. Meanwhile, the light directed toward the second common electrode 750 is reflected by the second common electrode 750, the first common electrode 730, the pixel electrode 710, or the like, and changes into right circularly polarized light. In addition, the light may be reflected not only on the electrodes 710, 730, and 750 of the organic light emitting diode 70 but also on various metal wires. Right circularly polarized light is emitted to the outside via the cholesteric liquid crystal film 585, the phase retardation plate 583, and the polarizing plate 581.

As described above, in the organic light emitting diode display 100 according to the first exemplary embodiment of the present invention, the light emitted from the organic light emitting diode is emitted when the light emitted from the organic light emitting element is emitted to the outside, rather than when the light flowing from the outside is reflected and then exits to the outside. The amount is relatively small.

Therefore, the organic light emitting diode display 100 may effectively suppress reflection of external light while minimizing the loss of light emitted from the organic light emitting layer 720 to the outside.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. 5.

As illustrated in FIG. 5, the optical member 59 of the organic light emitting diode display 200 according to the second exemplary embodiment includes a polarizing plate 591, a selective reflective film 592, and a phase retardation plate 593. Include. That is, the optical member 59 includes a phase retardation plate 593, a selective reflection film 592, and a polarizing plate 591 which are sequentially arranged on the sealing member 210.

As the selective reflection film 592, a dual brightness enhancement film (DBEF) is used. Hereinafter, in the second embodiment of the present invention, the selective reflective film 592 is referred to as a reflective polarizing film.

The reflective polarizing film (DBEF) 592 passes light that coincides with the polarization axis, but reflects light that does not coincide with the polarization axis. That is, the polarizing plate 591 is different from the reflective polarizing film 592 in that it absorbs light that does not coincide with the polarization axis.

The polarizing plate 591 has a polarization axis in the same direction as the reflective polarizing film 592. And the bridge | sticker between the optical axis of the phase retardation plate 593 and the polarization axis of the reflective polarizing film 592 is 45 degree | times.

In addition, the pixel defining layer 190 may have a black or gray color. Accordingly, the pixel defining layer 190 suppresses the reflection of the light incident from the outside. Meanwhile, in the second embodiment of the present invention, the pixel defining layer 190 has a black or gray color, but is not necessarily limited thereto. Therefore, the pixel defining layer 190 may not have a color.

By such a configuration, the organic light emitting diode display 200 may effectively suppress reflection of external light to improve visibility while minimizing the loss of light emitted from the organic light emitting layer 720 to the outside.

Hereinafter, the light emitted from the organic light emitting layer 720 to the outside while the optical member 59 of the organic light emitting diode display 200 according to the second exemplary embodiment of the present invention effectively suppresses reflection of external light with reference to FIGS. 6 and 7. Let's look at how to minimize the loss of

First, referring to FIG. 6, the path of light flowing into the inside through the optical member 59 from the outside will be described.

External light is linearly polarized in the direction of the polarization axis of the polarizing plate 591 while passing through the polarizing plate 591. The linearly-lighted light passes through the reflective polarizing film 592 and is directed to the phase retardation plate 593 without substantial loss. The linearly polarized light changes to circularly polarized light through the phase retardation plate 593 which is a quarter wave plate. At this time, the optical axis of the phase retardation plate 593 is shifted by 45 degrees from the polarization axis of the reflective polarizing film 592. That is, the pier between the optical axis of the phase retardation plate 593 and the polarization axis of the reflective polarizing film 592 is 45 degrees.

As described above, since the intersection between the axial direction of the linearly-lighted light and the optical axis direction of the phase retardation plate 593 is 45 degrees, the linearly polarized light changes to circularly polarized light while passing through the phase retardation plate 593. In this case, circularly polarized light is right circularly polarized light. However, the second embodiment according to the present invention is not limited thereto. Therefore, the light passing through the phase delay plate 593 may be left circularly polarized light.

The right circularly polarized light passing through the phase retardation plate 593 is reflected between the second common electrode 750 and the first common electrode 730 to be substantially extinguished by the destructive interference as described above. In addition, some light is reflected from the second common electrode 750, the first common electrode 730, the pixel electrode 710, and the like and is directed back to the phase delay plate 593. At this time, the light that is the right circularly polarized light is changed to the left circularly polarized light. The left circularly polarized light is linearly polarized while passing through the phase retardation plate 593, wherein the axial direction of the linearly polarized light is a direction crossing the polarization axis of the reflective polarizing film 592. Therefore, the light does not pass through the reflective polarizing film 592 and is reflected back through the phase delay plate 593 to the second common electrode 750. Further, the linearly polarized light passes through the phase retardation plate 593 and changes to left circularly polarized light. In addition, while reflected between the second common electrode 750 and the first common electrode 730, a considerable amount of disappearance due to destructive interference.

Again, the light that is left circularly polarized while being reflected from the second common electrode 750, the first common electrode 730, the pixel electrode 710, or the like is now converted into right circularly polarized light. The right circularly polarized light is linearly polarized while passing through the phase retardation plate 593. At this time, the axial direction of the linearly polarized light is substantially the same direction as the polarization axis of the reflective polarizing film 592. Here, substantially the same is because light shows slightly different behavior for each wavelength band. Light belonging to the wavelength band of the visible light is in substantially the same direction as the polarization axis of the reflective polarizing film 592. Therefore, the linearly polarized light passes through the reflective polarizing film 592 and the polarizing plate 591 in order to be emitted to the outside.

As described above, since external light passes through the optical member 59 and is reflected between the second common electrode 750 and the first common electrode 730 several times, the light is extinguished by a destructive interference. 200 can effectively suppress external light reflection.

In addition, as illustrated in FIG. 5, the pixel defining layer 190 having a black or gray color may absorb light to help suppress reflection of external light more effectively.

Next, the path of light emitted from the organic emission layer 720 to the outside will be described with reference to FIG. 7.

The light emitted from the organic emission layer 720 passes through the first common electrode 730, the transmissive film 600, the second common electrode 750, and the phase retardation plate 593 to the reflective polarizing film 592. Headed. At this time, light is a state in which various phases are mixed.

The light having the same component as the polarization axis of the reflective polarizing film 592 among the light passing through the phase retardation plate 593 passes through the reflective polarizing film 592, and the rest of the light is reflected back to the phase retardation plate 593. Here, light passing through the reflective polarizing film 592 is linearly polarized. The linearly polarized light passes through the polarizer 591 without any substantial loss and is emitted to the outside. Meanwhile, the light reflected by the reflective polarizing film 592 is directed to the second common electrode 750 through the phase delay plate 593. At this time, the light may be left circularly polarized in a considerable amount while passing through the phase retardation plate 593. The left circularly polarized light directed toward the second common electrode 750 is reflected into the second common electrode 750, the first common electrode 730, the pixel electrode 710, and the like, and changes to right circularly polarized light. In addition, the light may be reflected not only on the electrodes 710, 730, and 750 of the organic light emitting diode 70 but also on various metal wires. The right circularly polarized light is emitted to the outside via the phase retardation plate 593, the reflective polarizing film 592, and the polarizing plate 591.

As described above, in the organic light emitting diode display 200 according to the second exemplary embodiment, the light emitted from the organic light emitting diode 70 is emitted to the outside than when the light flowing from the outside is reflected and exits again. The amount of loss is relatively small.

Accordingly, the organic light emitting diode display 200 may effectively suppress reflection of external light and minimize loss of light emitted from the organic light emitting layer 720 to the outside.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the following claims. Those who are engaged in the technology field will understand easily.

1 is a layout view of an organic light emitting diode display according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.

3 is a block diagram illustrating a path of light introduced into the organic light emitting diode display of FIG. 1 from the outside.

4 is a diagram illustrating a path in which light generated by an organic light emitting diode of the organic light emitting diode display of FIG. 1 is emitted to the outside.

5 is a cross-sectional view of an organic light emitting diode display according to a second exemplary embodiment of the present invention.

FIG. 6 is a diagram illustrating a path of light introduced into the OLED display of FIG. 5 from the outside.

FIG. 7 is a diagram illustrating a path in which light generated by an organic light emitting diode of the organic light emitting diode display of FIG. 5 is emitted to the outside.

Claims (13)

A substrate member; A pixel electrode formed on the substrate member; An organic emission layer formed on the pixel electrode; A first common electrode formed on the organic emission layer; A transmission membrane formed on the first common electrode; A second common electrode formed on the transmission membrane; A selective reflective film formed on the second common electrode; A polarizer formed on the selective reflection film; And A phase retardation plate disposed between the polarizer and the second common electrode An organic light emitting display device comprising a. In claim 1, The selective reflection film is a cholesteric liquid crystal (CLC) film, The phase delay plate is disposed between the polarizing plate and the cholesteric liquid crystal film. In claim 2, The cholesteric liquid crystal film passes one of left circularly polarized light and right circularly polarized light, and reflects the other. 4. The method of claim 3, The linearly polarized light passing through the polarizing plate changes to circularly polarized light when passing through the phase retardation plate. In claim 4, The phase retardation plate is a quarter wave plate, And an pier between an optical axis of the phase retardation plate and a polarization axis of the polarizing plate is 45. In claim 1, The selective reflective film is a reflective polarizing film, The phase retardation plate is disposed between the organic light emitting element and the reflective polarizing film. In claim 6, The polarizing plate and the reflective polarizing film have the same polarization axis. In claim 7, The linearly polarized light passing through the reflective polarizing film changes to circularly polarized light when passing through the phase retardation plate. In claim 8, The phase retardation plate is a quarter wave plate, And an pier between an optical axis of the phase retardation plate and a polarization axis of the polarizing plate is 45. In claim 1, At least one of the first common electrode and the second common electrode is formed of a transflective layer. In claim 2, The transflective layer is made of at least one metal of magnesium (Mg), silver (Ag), calcium (Ca), lithium (Li), chromium (Cr), and aluminum (Al). The method according to any one of claims 1 to 11, And a pixel defining layer formed on the substrate member with an opening that exposes the pixel electrode. The pixel defining layer has a black or gray color. In claim 12, The pixel defining layer is disposed under the first common electrode.

Images